ABC News(SANFORD, Fla.) -- Two witnesses called by the prosecution Friday described George Zimmerman as being on the losing end of a fight with Trayvon Martin in the moments before Zimmerman shot the Florida teenager.

However, an EMT who was on the scene immediately following the shooting testified that she treated Zimmerman for five minutes before releasing him into police care.

Zimmerman, 29, is facing second degree murder charges for shooting and killing Martin on Feb. 26, 2012. He maintains he shot Martin, 17, in self defense after his head was slammed several times against a concrete sidewalk.

John Good told the jury Friday that he yelled "stop" at both men shortly after realizing that what he at first assumed to be a dog attack was actually two men grappling on the ground.

"I said cut it out. I'm calling 911 because it was getting serious," said Good.

Good testified that he saw what he believed to be Martin on top of Zimmerman.

"The color on top was dark and the color at bottom was…red," Good said referring to the men's clothing.

At another point he told the court that the person on the bottom had "lighter skin color."

Zimmerman is a white Hispanic who was wearing a red and black jacket that night. Martin, who was black, was wearing a dark sweatshirt.

"The person on the bottom, I could hear a 'Help,'" he said.

Under cross examination by Zimmerman's lawyer, Good said he believes he saw Martin on top punching Zimmerman "MMA style," a reference to mixed martial arts.

"The person on top was ground and pounding the person on the bottom?" asked Zimmerman attorney Mark O'Mara. "Correct," said Good.

Good testified that he did not see Martin banging Zimmerman's head on the concrete.

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His account was accompanied by a recording of Good's 911 call to police in which he is heard telling the dispatcher that he heard a gunshot.

"I'm pretty sure the guy is dead out there. Holy sh**. .. There's a black guy down and he's been shot. It looks like he is dead," Good said.

Jonathan Manalo, who also lived near the shooting scene, testified today that Zimmerman told him just moments after Martin was killed to call his wife and say "Just tell her I shot someone."

Manalo did not see the confrontation between Zimmerman and the unarmed teenager, but walked outside of his home with a flashlight moments after hearing a gunshot.

He said Zimmerman looked like he had "got his butt beat," but was "speaking clearly."

Manalo took photos of Zimmerman's bloody nose, the back of his bloody head, Martin's body lying face down in the grass and a flashlight on the ground.

He says Zimmerman told him as he approached, "This guy was beating me up. I was defending myself and I shot him."

Stacy Livingston, an EMT who arrived on the scene, said she treated Zimmerman -- who was complaining of dizziness -- for five minutes before releasing him into police custody.

In addition, Police Officer Tim Smith told the court he took Zimmerman into custody on the night of the shooting and that the back of Zimmerman's jacket was wet and had bits of grass on it, and the back of his pants appeared wet. It had been raining that night and the ground was wet.

So far no witness has testified about who started the fight and there have been conflicting accounts about who was on top during the fight. Selma Mora, another witness, testified Thursday that Zimmerman was on top of Martin in the moments before a gunshot ended the fight.

Mora told the court Thursday that at some point she saw a man in "patterns between black and red" on top, indicating Zimmerman.

"One of them was on the ground, and the other one was on top in position like a rider," Mora, who speaks Spanish, testified through a translator.

Mora told the court that after the shooting Zimmerman was pacing and putting his hands on his head, but didn't appear to have trouble walking and didn't stagger, or stumble.